Category

Published on

25 Feb 2015

Abstract

Nanoelectromechanical systems (NEMS) are microelectromechanical systems (MEMS) with dimensions in the submicron region. Carbon nanotubes, whose dimensions can be several nanometers, are good examples of nanostructures that can be used in NEMS.

Electromechnical systems contain a structure and a substrate, and the structure is actuated by applying the potential difference or voltage between them. When the voltage is applied, opposite charges accumulate on the structure and substrate, and because of the electrostatic force the structure deflects. The deflection of the structure changes the electrostatic field and hence the charges redistribute themselves resulting in change in the electrostatic force and then the deflection of the structure. Equilibrium is obtained once the electrostatic force balances the elastic resistance of the structure. As the voltage is increased, the equilibrium deflection of the structure also increases. After a specific voltage, also called as pull-in voltage, the elastic resistance can no longer balance the increasing electrostatic force, the structure collapses and touches the substrate.

Van der Waals forces are the weak non-bonded interaction between atoms. These forces vanish rapidly as the distance between the atoms increases. The Van der Waals forces between nanostructure seperated by several nanometers can be significant and hence also needs to be accounted while modeling NEMS.

The present tool simulates the pull-in behavior of carbon nanotube based NEMS with cantilever boundary conditions for various dimensions of the carbon nanotube, for different applied voltages, for different initial gaps between the substrate and the structure. It also helps one to study the effect of Van der Waals forces on the above studies.